When I first became a teacher 10 years ago, I envisioned a long career helping countless children reach their potential and go on to accomplish great things. By all measures, I’m succeeding — but it’s no longer enough to sustain me in this profession. Next month, as teachers and students return to to MS 391 in The Bronx, I won’t be among them.

The decision to leave the classroom was among the most difficult I’ve ever made, but I feel like my career is stuck in neutral, with no clear path of advancement.

A new report from TNTP, a national nonprofit focused on teacher quality, shows that my experience is sadly typical. It surveyed teachers in New York City and across the country, focusing on “Irreplaceables” — teachers who are so successful that it can take schools as many as 11 hires to find just one.

The report found that schools nationwide lose tens of thousands of Irreplaceables a year that they should’ve been able to keep. Principals aren’t trying hard enough to keep their best teachers or build school cultures that will make them excited to stay. Many don’t even bother to ask great teachers to return for another year.

And most schools in New York City and elsewhere can’t offer raises or new leadership roles to top teachers — though TNTP found that both could keep Irreplaceables in the classroom longer.

I know how new career pathways can make a big difference. Last year, I jumped at the chance to participate in the city’s Master Teacher program. I earned more in exchange for spending extra time mentoring my peers, writing curricula and running professional development.

That program sent a clear message to great teachers: Your school needs you. That helped keep me in the classroom after I’d started to think about leaving.

But funding for the Master Teacher program at my school was rescinded this year, leaving teachers like me few options for professional growth.

Compounding the problem is that schools let their weakest teachers stay in the classroom indefinitely. New York City keeps its very best and very worst teachers at nearly identical rates, TNTP found, even though they achieve dramatically different results with their students.

That sends a message, too.

So what can New York City do to stop the flight of great teachers?

First, the city and the United Federation of Teachers must finally agree on a fair, meaningful teacher-evaluation system. Then schools can identify their best teachers and work harder to keep them — and give better support to struggling teachers.

Second, find new ways to recognize great teachers and give them opportunities to extend their reach. Bringing back Master Teacher would be a good start.

We also need to be more thoughtful about how we reward success. As a member of Educators 4 Excellence, a teacher-led organization, I was part of a team that recommended higher starting salaries, bonuses and career ladders so teachers could take on leadership positions in their schools.

Finally, the city needs to hold principals accountable for fixing school cultures that drive top teachers away. This means improving working conditions and creating environments of mutual respect and trust. (And give principals credit on their own performance reviews for retaining great teachers.)

But it also means refusing to turn a blind eye to poor teaching. Struggling teachers deserve support and a reasonable chance to improve. But if they can’t, they shouldn’t stay in the classroom.

I’ve decided to pursue a career in education policy. I won’t work one-on-one with students, but I hope to help put effective teachers in every classroom. It starts with keeping our best educators engaged and recognizing the important contributions they make each day in the lives of children.

Lori Wheal taught English-language arts at MS 391 in The Bronx for the past 10 years.